Effects of natural phenolic compound carvacrol on the human gastric adenocarcinoma (AGS) cells in vitro

The recent discovery of a promising pharmacological scaffold derived from carvacrol: A review

Carvacrol, called CA, is a dynamic phytoconstituent characterized by a phenol ring abundantly sourced from various natural reservoirs. This versatile scaffold serves as a pivotal template for the design and synthesis of novel drug molecules, harboring promising biological activities. The active sites positioned at C-4, C-6, and the hydroxyl group (-OH) of CA offer fertile ground for creating potent drug candidates from a pharmacological standpoint. In this comprehensive review, we delve into diverse synthesis pathways and explore the biological activity of CA derivatives. We aim to illuminate the potential of these derivatives in discovering and developing efficacious treatments against a myriad of life-threatening diseases. By scrutinizing the structural modifications and pharmacophore placements that enhance the activity of CA derivatives, we aspire to inspire the innovation of novel therapeutics with heightened potency and effectiveness.

The Emerging Role of Natural Products in Cancer Treatment

The exploration of natural products as potential agents for cancer treatment has garnered significant attention in recent years. In this comprehensive review, we delve into the diverse array of natural compounds, including alkaloids, carbohydrates, flavonoids, lignans, polyketides, saponins, tannins, and terpenoids, highlighting their emerging roles in cancer therapy. These compounds, derived from various botanical sources, exhibit a wide range of mechanisms of action, targeting critical pathways involved in cancer progression such as cell proliferation, apoptosis, angiogenesis, and metastasis. Through a meticulous examination of preclinical and clinical studies, we provide insights into the therapeutic potential of these natural products across different cancer types. Furthermore, we discuss the advantages and challenges associated with their use in cancer treatment, emphasizing the need for further research to optimize their efficacy, pharmacokinetics, and delivery methods. Overall, this review underscores the importance of natural products in advancing cancer therapeutics and paves the way for future investigations into their clinical applications.

Chemical and Bioactive Evaluation of Essential Oils from Edible and Aromatic Mediterranean Lamiaceae Plants

The Lamiaceae family, which includes several well-known aromatic plants, is scientifically relevant due to its essential oils (EOs). In this work, four EOs from Mediterranean species, namely Origanum vulgare L., Rosmarinus officinalis L., Salvia officinalis L., and Thymus vulgaris L., were evaluated for their volatile profiles and the biological activity in vitro to assess their potential use in the food and cosmetic sector. GC/MS analysis revealed dominant compounds, such as carvacrol, thymol, and eucalyptol. Regarding biological action, the samples exhibited antioxidant, cytotoxic, anti-inflammatory, antimicrobial, and antifungal activities, with O. vulgare and T. officinalis standing out. T. vulgaris showed the lowest EC50 in the reducing power assay, and O. vulgare had the lowest EC50 in the DPPH assay. Most EOs also displayed excellent anti-inflammatory responses and antifungal properties, with O. vulgare and T. vulgaris also demonstrating antibacterial activity. All EOs from Mediterranean species showed cytotoxicity against tumoral cell lines. Overall, the selected EOs stood out for their interesting bioactivities, with the obtained results underscoring their potential as natural preservatives and bioactive agents in various industrial applications, including food, pharmaceuticals, and cosmetics.

An Overview of the Spices Used for the Prevention and Potential Treatment of Gastric Cancer

Gastric cancer (GC) ranks third in terms of cancer-related deaths and is the fifth most commonly diagnosed type of cancer. Its risk factors include Helicobacter pylori infection, Epstein-Barr virus infection, the consumption of broiled and charbroiled animal meats, salt-preserved and smoke-enhanced foods, alcohol drinking, tobacco smoking, exposure to ionizing radiation, and positive family history. The limited effectiveness of conventional therapies and the widespread risk factors of GC encourage the search for new methods of treatment and prevention. In the quest for cheap and commonly available medications, numerous studies focus on herbal medicine, traditional brews, and spices. In this review, we outline the potential use of spices, including turmeric, ginger, garlic, black cumin, chili pepper, saffron, black pepper, rosemary, galangal, coriander, wasabi, cinnamon, oregano, cardamom, fenugreek, caraway, clove, dill, thyme, Piper sarmentosum, basil, as well as the compounds they contain, in the prevention and treatment of GC. We present the potential molecular mechanisms responsible for the effectivity of a given seasoning substance and their impact on GC cells. We discuss their potential effects on proliferation, apoptosis, and migration. For most of the spices discussed, we also outline the unavailability and side effects of their use.

Helicobacter pylori infection in humans and phytotherapy, probiotics, and emerging therapeutic interventions: a review

The global prevalence of Helicobacter pylori (H. pylori) infection remains high, indicating a persistent presence of this pathogenic bacterium capable of infecting humans. This review summarizes the population demographics, transmission routes, as well as conventional and novel therapeutic approaches for H. pylori infection. The prevalence of H. pylori infection exceeds 30% in numerous countries worldwide and can be transmitted through interpersonal and zoonotic routes. Cytotoxin-related gene A (CagA) and vacuolar cytotoxin A (VacA) are the main virulence factors of H. pylori, contributing to its steep global infection rate. Preventative measures should be taken from people's living habits and dietary factors to reduce H. pylori infection. Phytotherapy, probiotics therapies and some emerging therapies have emerged as alternative treatments for H. pylori infection, addressing the issue of elevated antibiotic resistance rates. Plant extracts primarily target urease activity and adhesion activity to treat H. pylori, while probiotics prevent H. pylori infection through both immune and non-immune pathways. In the future, the primary research focus will be on combining multiple treatment methods to effectively eradicate H. pylori infection.

Reactive Oxygen Species and H. pylori Infection: A Comprehensive Review of Their Roles in Gastric Cancer Development

Gastric cancer (GC) is the fifth most common cancer worldwide and makes up a significant component of the global cancer burden. Helicobacter pylori (H. pylori) is the most influential risk factor for GC, with the International Agency for Research on Cancer classifying it as a Class I carcinogen for GC. H. pylori has been shown to persist in stomach acid for decades, causing damage to the stomach's mucosal lining, altering gastric hormone release patterns, and potentially altering gastric function. Epidemiological studies have shown that eliminating H. pylori reduces metachronous cancer. Evidence shows that various molecular alterations are present in gastric cancer and precancerous lesions associated with an H. pylori infection. However, although H. pylori can cause oxidative stress-induced gastric cancer, with antioxidants potentially being a treatment for GC, the exact mechanism underlying GC etiology is not fully understood. This review provides an overview of recent research exploring the pathophysiology of H. pylori-induced oxidative stress that can cause cancer and the antioxidant supplements that can reduce or even eliminate GC occurrence.

Current Understanding of Polyphenols to Enhance Bioavailability for Better Therapies

In recent years, plant polyphenols have become a popular focus for the development of novel functional foods. Polyphenols, a class of bioactive compounds, including flavonoids, phenolic acids, and lignans, are commonly found in plant-based diets with a variety of biological actions, including antioxidant, anti-inflammatory, and anticancer effects. Unfortunately, polyphenols are not widely used in nutraceuticals since many of the chemicals in polyphenols possess poor oral bioavailability. Thankfully, polyphenols can be encapsulated and transported using bio-based nanocarriers, thereby increasing their bioavailability. Polyphenols' limited water solubility and low bioavailability are limiting factors for their practical usage, but this issue can be resolved if suitable delivery vehicles are developed for encapsulating and delivering polyphenolic compounds. This paper provides an overview of the study of nanocarriers for the enhancement of polyphenol oral bioavailability, as well as a summary of the health advantages of polyphenols in the prevention and treatment of several diseases.

Anti-Cholinesterase and Anti-α-Amylase Activities and Neuroprotective Effects of Carvacrol and p-Cymene and Their Effects on Hydrogen Peroxide Induced Stress in SH-SY5Y Cells

Several researchers have demonstrated the health and pharmacological properties of carvacrol and p-cymene, monoterpenes of aromatic plants. This study investigated these compounds' possible anti-cholinesterase, anti-α-amylase, and neuroprotective effects. We evaluated the anti-acetylcholinesterase and anti-α-amylase activities at different concentrations of the compounds. The maximum non-toxic dose of carvacrol and p-cymene against SH-SY5Y neuroblastoma cells was determined using an MTT assay. The neuroprotective effects of the compounds were evaluated on H₂O₂-induced stress in SH-SY5Y cells, studying the expression of caspase-3 using Western blotting assays. Carvacrol showed inhibitory activities against acetylcholinesterase (IC50 = 3.8 µg/mL) and butyrylcholinesterase (IC₅₀ = 32.7 µg/mL). Instead, the anti-α-amylase activity of carvacrol resulted in an IC₅₀ value of 171.2 μg/mL After a pre-treatment with the maximum non-toxic dose of carvacrol and p-cymene, the expression of caspase-3 was reduced compared to cells treated with H₂O₂ alone. Carvacrol and p-cymene showed in vitro anti-enzymatic properties, and may act as neuroprotective agents against oxidative stress. Further studies are necessary to elucidate their possible use as coadjutants in preventing and treating AD in diabetic patients.

Effects of Dietary Phytochemicals on DNA Damage in Cancer Cells

With the increasing incidence of cancer worldwide, the prevention and treatment of cancer have garnered considerable scientific attention. Traditional chemotherapeutic drugs are highly toxic and associated with substantial side effects; therefore, there is an urgent need for developing new therapeutic agents. Dietary phytochemicals are important in tumor prevention and treatment because of their low toxicity and side effects at low concentrations; however, their exact mechanisms of action remain obscure. DNA damage is mainly caused by physical or chemical factors in the environment, such as ultraviolet light, alkylating agents and reactive oxygen species that cause changes in the DNA structure of cells. Several phytochemicals have been shown inhibit the occurrence and development of tumors by inducing DNA damage. This article reviews the advances in phytochemical research; particularly regarding the mechanisms related to DNA damage and provide a theoretical basis for future chemoprophylaxis research.

The biological and therapeutic potentials of Cyclotrichium genus: a systematic review

The genus Cyclotrichium includes nine species that are mainly distributed in Turkey, Lebanon, Iraq, and Iran, and are used in the kitchen, and also in complementary medicine to treat various diseases. During recent years, considerable progress has been made in analyzing their phytochemical composition in parallel with their antimicrobial properties and their therapeutic potentials. This study reviews the present knowledge about investigations on antimicrobial, insecticidal, and anticancer properties of the essential oils and any other purified chemical compounds of the Cyclotrichium species. Various phytochemicals have been isolated from the extracts of the plants of this genus having significant biological and therapeutic potentials. In conclusion, these gathered data strongly support the viewpoint that the species belonging to the genus Cyclotrichium have various biological and pharmaceutical activities to treat various diseases including cancer in addition to the remarkable antimicrobial and insecticidal potential with no or minimal health and environmental hazards.

Polyphenols as Plant-Based Nutraceuticals: Health Effects, Encapsulation, Nano-Delivery, and Application

Plant polyphenols have attracted considerable attention because of their key roles in preventing many diseases, including high blood sugar, high cholesterol, and cancer. A variety of functional foods have been designed and developed with plant polyphenols as the main active ingredients. Polyphenols mainly come from vegetables and fruits and can generally be divided according to their structure into flavonoids, astragalus, phenolic acids, and lignans. Polyphenols are a group of plant-derived functional food ingredients with different molecular structures and various biological activities including antioxidant, anti-inflammatory, and anticancer properties. However, many polyphenolic compounds have low oral bioavailability, which limits the application of polyphenols in nutraceuticals. Fortunately, green bio-based nanocarriers are well suited for encapsulating, protecting, and delivering polyphenols, thereby improving their bioavailability. In this paper, the health benefits of plant polyphenols in the prevention of various diseases are summarized, with a review of the research progress into bio-based nanocarriers for the improvement of the oral bioavailability of polyphenols. Polyphenols have great potential for application as key formulations in health and nutrition products. In the future, the development of food-grade delivery carriers for the encapsulation and delivery of polyphenolic compounds could well solve the limitations of poor water solubility and low bioavailability of polyphenols for practical applications.

A Focused Insight into Thyme: Biological, Chemical, and Therapeutic Properties of an Indigenous Mediterranean Herb

A perennial wild shrub from the Lamiaceae family and native to the Mediterranean region, thyme is considered an important wild edible plant studied for centuries for its unique importance in the food, pharmaceutical, and cosmetic industry. Thyme is loaded with phytonutrients, minerals and vitamins. It is pungent in taste, yet rich in moisture, proteins, crude fiber, minerals and vitamins. Its chemical composition may vary with geographical location but is mainly composed of flavonoids and antioxidants. Previous studies have illustrated the therapeutic effects of thyme and its essential oils, especially thymol and carvacrol, against various diseases. This is attributed to its multi-pharmacological properties that include, but are not limited to, antioxidant, anti-inflammatory, and antineoplastic actions. Moreover, thyme has long been known for its antiviral, antibacterial, antifungal, and antiseptic activities, in addition to remarkable disruption of microbial biofilms. In the COVID-19 era, some thyme constituents were investigated for their potential in viral binding. As such, thyme presents a wide range of functional possibilities in food, drugs, and other fields and prominent interest as a nutraceutical. The aims of the current review are to present botanical and nutritive values of this herb, elaborate its major constituents, and review available literature on its dietetic and biological activities.

Terpenes and terpenoids as main bioactive compounds of essential oils, their roles in human health and potential application as natural food preservatives

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Terpenes and terpenoids are the main bioactive compounds of essential oils (EOs).

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EOs and their major constituents confer several biological activities.

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EOs are potential as natural food preservatives.

Essential oils (EOs) are volatile and concentrated liquids extracted from different parts of plants. Bioactive compounds found in EOs, especially terpenes and terpenoids possess a wide range of biological activities including anticancer, antimicrobial, anti-inflammatory, antioxidant, and antiallergic. Available literature confirms that EOs exhibit antimicrobial and food preservative properties that are considered as a real potential application in food industry. Hence, the purpose of this review is to present an overview of current knowledge of EOs for application in pharmaceutical and medical industries as well as their potential as food preservatives in food industry.

Therapeutic Potential of Certain Terpenoids as Anticancer Agents: A Scoping Review

Cancer is a life-threatening disease and is considered to be among the leading causes of death worldwide. Chemoresistance, severe toxicity, relapse and metastasis are the major obstacles in cancer therapy. Therefore, introducing new therapeutic agents for cancer remains a priority to increase the range of effective treatments. Terpenoids, a large group of secondary metabolites, are derived from plant sources and are composed of several isoprene units. The high diversity of terpenoids has drawn attention to their potential anticancer and pharmacological activities. Some terpenoids exhibit an anticancer effect by triggering various stages of cancer progression, for example, suppressing the early stage of tumorigenesis via induction of cell cycle arrest, inhibiting cancer cell differentiation and activating apoptosis. At the late stage of cancer development, certain terpenoids are able to inhibit angiogenesis and metastasis via modulation of different intracellular signaling pathways. Significant progress in the identification of the mechanism of action and signaling pathways through which terpenoids exert their anticancer effects has been highlighted. Hence, in this review, the anticancer activities of twenty-five terpenoids are discussed in detail. In addition, this review provides insights on the current clinical trials and future directions towards the development of certain terpenoids as potential anticancer agents.

Essential oils as anticancer agents: Potential role in malignancies, drug delivery mechanisms, and immune system enhancement

Cancer retains a central place in fatality rates among the wide variety of diseases known world over, and the conventional synthetic medicaments, albeit used until now, produce numerous side effects. As a result, newer, better, and safer alternatives such as natural plant products, are gravely required. Essential oils (EOs) offer a plethora of bioactivities including antibacterial, antiviral, antioxidant, and anticancer properties, therefore, the use of EOs in combination with synthetic drugs or aromatherapy continues to be popular in many settings. In view of the paramount importance of EOs and their potential bioactivities, this review summarizes the current knowledge on the interconnection between EOs and cancer treatment. In particular, the current review presents an updated summary of the chemical composition of EOs, their current applications in cancer treatments based on clinical studies, and the mechanism of action against the cancer cell lines. Similarly, an overview of using EOs in aromatherapy and enhancing immunity during cancer treatment is provided. Further, this review focuses on the recent technological advancements such as the loading of EOs using protein microspheres, ligands, or nanoemulsions/nanoencapsulation, which offer multiple benefits in cancer treatment via site-specific and target-oriented delivery of drugs. The continuing clinical studies of EOs implicate that their pharmacological applications are a rewarding research area.

Molecular insights on chemopreventive and anticancer potential of carvacrol: Implications from solid carcinomas

Globally, cancer is one of the deadliest diseases, estimated to cause 9.9 million deaths in 2020. Conventional cancer treatments commonly involve mono-chemotherapy or a combination of radiotherapy and mono-chemotherapy. However, the negative side effects of these approaches have been extensively reported and have prompted the search for new therapeutic drugs. Over the past few years, numerous dietary agents, medicinal plants, and their phytochemicals gained considerable therapeutic importance because of their anticancer, antiviral, anti-inflammatory, and antioxidant activities. Recent years have shown that essential oils possess therapeutic effects against numerous cancers. They are primarily used due to their lesser side effects than standard chemotherapeutic drugs. Carvacrol (CRV) is a phenolic monoterpenoid found in essential oils of oregano, thyme, pepperwort, wild bergamot, and other plants. Numerous anticancer reports of CRV substantiated that the main mechanistic action of CRV involves reduction in the viability of cancer cells and induction of apoptosis via both intrinsic and extrinsic pathways. CRV also obstructs the migration and invasion of cells leading to the suppressed proliferation rate. Furthermore, CRV mediates augmented ROS generation resulting in DNA damage and also halts the progression of cell cycle. Treatment of CRV modulates the expression of apoptotic proteins (Bax, Bad) and molecular targets of various signaling pathways (PI3K/AKT/mTOR, MAPKs, and Notch) in multiple solid carcinomas. Hence, this review aimed to acquire and disseminate the knowledge of chemopreventive and anticancer effects of CRV and the mechanisms of action already described for the compound against numerous cancers, including solid carcinomas, to guide future research. PRACTICAL APPLICATIONS: Development and formulation of phytocompound based anticancer drug agents to counteract the aftereffects of chemotherapeutic drugs is a propitious approach. CRV is a monoterpenoid consisting of a phenolic group obtained from the essential oils of oregano and thyme. These plants are being used as food flavoring spice and as fragrance ingredient in various cosmetic formulations. For the use of CRV as an efficient chemopreventive agent, different therapeutic interactions of CRV along with its targeted pathways and molecules, involved in the regulation of onset and progression of various types of solid carcinomas, need to be studied and explored thoroughly.

Anticancer activity of monoterpenes: a systematic review

Secondary metabolites have been recognized for centuries as medicinal agents, in particular monoterpenes which have been the target of research in the discovery of antineoplastic drugs, as they have potential antitumor effect and low toxicity and are used as additives in foods and cosmetics. Another advantage of monoterpenes is structural diversity, which gives greater plasticity when interacting with cells. The purpose of this review was to summarize and critically discuss the anticancer potential of monoterpenes and their respective mechanisms of action. A systematic review of articles in the MEDLINE/PubMed, Web of Science, Scopus and Science Direct electronic databases was independently conducted by three reviewers using the combination of the following keywords: monoterpenes AND anticancer AND in vitro. Restriction in selecting articles followed pre-established inclusion and exclusion criteria by the reviewers, and also a time limitation with works published between 2015 and 2019 being selected. In total, 39 works were deemed eligible for inclusion in the final review. Monoterpenes have cytotoxic activity in a wide variety of tumor cell lines, and mainly appear to exert this effect by inducing apoptosis caused by oxidative stress. In addition, improved use of monoterpenes when used in drug delivery systems and the synergistic effect with conventional chemotherapeutic drugs are reported. These findings validate this class of compounds as a promising source of chemotherapeutic drugs yet to be explored.

Effects of 1,25 Dihydroxyvitamin D3 on Human Retinal Pigment Epithelial Cell Lines

PURPOSE

To assess the effects of 1,25 dihydroxyvitamin D₃ (vitamin D₃) either alone or under oxidative damage on human retinal pigment epithelium cell lines.

METHODS

The human retinal pigment epithelial cell lines were pretreated with hydrogen peroxide with different concentrations (100-1000 μM) and durations (4, 12 and 24 h) to determine the appropriate dose. A group of cells were treated with vitamin D₃ alone, and another group of cells were co-treated with different concentrations of (10-100 nM) vitamin D₃ and hydrogen peroxide. Anti-cytotoxic, anti-apoptotic and anti-genotoxic effects of vitamin D₃ on the hydrogen peroxide treated cell line were evaluated. In addition, mitochondrial membrane potentials of treated cell lines were measured.

RESULTS

Vitamin D₃ showed statistically significant anti-cytotoxic effects and increased cell viability in all concentrations (p < 0.001). It has also significantly decreased the intracellular ROS generation at concentrations between 10-60 nM and increased intracellular reactive oxygen species in high doses over 90 nM (p < 0.01). When apoptosis was evaluated, vitamin D₃ caused statistically significant decrease in a dose-dependent manner (p < 0.001). In terms of DNA damage which was caused by oxidative stress, it was observed that vitamin D₃ significantly reduced the damage in a dose-dependent manner (p < 0.001). At the doses of 10-50 nM, vitamin D₃ significantly decreased the mitochondrial membrane potential (p < 0.01).

CONCLUSION

Our study suggests that 1,25 (OH)₂ D3 is capable for alleviating the oxidative damage in ARPE cell lines. With these results, vitamin D is thought to be a therapeutic alternative for the prevention of age-related macular degeneration. This warrants further investigations.

Physico-chemical characterization of carvacrol loaded zein nanoparticles for enhanced anticancer activity and investigation of molecular interactions between them by molecular docking

Carvacrol (CV), a monoterpene possesses wide range of biological activities but has limited application due to low aqueous solubility and poor bioavailability. To address this issue and enhance bioavailability and efficacy of carvacrol, lecithin stabilized zein nanoparticles were investigated. Precipitation method was used for synthesis of nanoparticles and characterized using various techniques. CV entrapped under optimized parameters has size around 250 nm with -15 mV zeta potential. SEM studies showed nanoparticles with spherical morphology and size in accordance with DLS studies. FTIR, NMR and DSC were used to determine the molecular interaction between CV and lecithin stabilized zein nanoparticles. Molecular docking studies were performed to understand the interaction between protein and drug at molecular level. Our results demonstrated the presence of two active sites within zein, showing strong binding interactions with carvacrol. The encapsulation efficiency of 78% with loading efficiency of 13% was obtained as per HPLC and UV-Vis studies. Cytotoxicity assay indicated that the CV loaded nanoparticles induce cytotoxicity against colon cancer (SW480) cells further confirmed by acridine orange and ethidium bromide dual staining assay. Fluorescent tagged nanoparticles revealed significant cellular uptake of drug. Our results suggest that CV can be conveniently delivered via oral route after incorporating into lecithin stabilized zein nanoparticles and may prove effective for colon cancer treatment.

Thymol Isolated from Thymus vulgaris L. Inhibits Colorectal Cancer Cell Growth and Metastasis by Suppressing the Wnt/β-Catenin Pathway

Purpose

Colorectal cancer (CRC) is one of the most commonly occurring cancers and is associated with high morbidity and mortality. Nevertheless, there is currently no safe and effective treatment for this condition. Thymol is a phenolic compound that is recognized as safe for use in food as well as medical and cosmetic fields. Increasing evidence has indicated that thymol exerts prominent antitumor effects in a variety of cancers, including CRC. However, how thymol elicits these effects on CRC and the associated underlying mechanisms remains unclear.

Methods

HCT116 and Lovo cells were treated with different concentrations of thymol. Cell Counting Kit-8 (CCK-8) and transwell migration and invasion assays were used to evaluate cell proliferation, migration, and invasion, respectively. Cell apoptosis and cell cycle distribution were measured by flow cytometry. RT-qPCR, Western blot, and immunohistochemistry were used to detect the expression of related genes and their protein products.

Results

In this study, we tested the antitumor activity of thymol extracted from a Chinese medicinal herb, Thymus vulgaris L. We show that thymol treatment in vitro inhibited cell proliferation and induced apoptosis and cell cycle arrest in CRC. Furthermore, in vivo treatment with 75 and 150 mg/kg thymol led to a significant decrease in tumor volume. Thymol administration induced CRC cell apoptosis through activation of the BAX/Bcl-2 signaling pathway. In addition, thymol suppressed CRC cell epithelial–mesenchymal transition (EMT), invasion, and metastasis via inhibiting the activation of the Wnt/β-catenin pathway, both in vitro and in vivo.

Conclusion

Thymol may prevent CRC progression through inhibition of the Wnt/β-catenin signaling pathway, highlighting its potential as a novel therapeutic option for the treatment of CRC.

Modulation of dysregulated cancer metabolism by plant secondary metabolites: A mechanistic review

Several signaling pathways and basic metabolites are responsible for the control of metabolism in both normal and cancer cells. As emerging hallmarks of cancer metabolism, the abnormal activities of these pathways are of the most noticeable events in cancer. This altered metabolism expedites the survival and proliferation of cancer cells, which have attracted a substantial amount of interest in cancer metabolism. Nowadays, targeting metabolism and cross-linked signaling pathways in cancer has been a hot topic to investigate novel drugs against cancer. Despite the efficiency of conventional drugs in cancer therapy, their associated toxicity, resistance, and high-cost cause limitations in their application. Besides, considering the numerous signaling pathways cross-linked with cancer metabolism, discovery, and development of multi-targeted and safe natural compounds has been a high priority. Natural secondary metabolites have exhibited promising anticancer effects by targeting dysregulated signaling pathways linked to cancer metabolism. The present review reveals the metabolism and cross-linked dysregulated signaling pathways in cancer. The promising therapeutic targets in cancer, as well as the critical role of natural secondary metabolites for significant anticancer enhancements, have also been highlighted to find novel/potential therapeutic agents for cancer treatment.

Antiproliferative and Anti-invasion Effects of Carvacrol on PC3 Human Prostate Cancer Cells through Reducing pSTAT3, pAKT, and pERK1/2 Signaling Proteins

BACKGROUND

One of the most effective parameters in the progression of the prostate cancer is interleukin (IL)-6 through affecting pSTAT3, pERK1/2, and pAKT cell signaling proteins. Carvacrol is an herbal antioxidant with antitumor effects. The purpose of this study was to investigate the effects of carvacrol on IL-6 gene expression, pSTAT3, pAKT, pERK1/2 cellular signaling proteins, and invasion in human prostate cancer PC3 cells.

METHODS

PC3 cell viability was evaluated by MTT assay with different concentrations of carvacrol (0-800 μM). IL-6 gene expression and cellular concentration of pSTAT3, pERK1/2, and pAKT were investigated using the real-time reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blotting technic, respectively. PC3 cell invasion was determined by invasion assay test.

RESULTS

Carvacrol IC50 for PC3 prostate cancer cells was 360 μM. Carvacrol led to a significant reduction (P < 0.05) for IL-6 gene expression in a dose-dependent manner compared to control. IL-6 protein reduced 41.5% and 52.7% when compared with control cells at 360 and 420 μM of carvacrol, respectively. Carvacrol led to a decline in pSTAT3, pAKT, and pERK1/2 above 360 μM compared to control. PC3 potential invasion was significantly reduced after treatment with carvacrol in a dose-dependent manner.

CONCLUSIONS

Decreased IL-6 protein level by carvacrol resulted in diminishing of pSTAT3, pERK1/2, and pAKT signaling proteins, which leads to the reduction of the cell survival, proliferation, and invasion in PC3 cells.

The compound 2-(naphthalene-2-thio)-5,8-dimethoxy-1,4-naphthoquinone induces apoptosis via reactive oxygen species-regulated mitogen-activated protein kinase, protein kinase B, and signal transducer and activator of transcription 3 signaling in human gastric cancer cells

Hit, Lead & Candidate Discovery It is reported that 1,4-naphthoquinones and their derivatives have potent antitumor activity in various cancers, although their clinical application is limited by observed side effects. To improve the therapeutic efficacy of naphthoquinones in the treatment of cancer and to reduce side effects, we synthesized a novel naphthoquinone derivative, 2-(naphthalene-2-thio)-5,8-dimethoxy-1,4-naphthoquinone (NTDMNQ). In this study, we explored the effects of NTDMNQ on apoptosis in gastric cancer cells with a focus on reactive oxygen species (ROS) production. Our results demonstrated that NTDMNQ exhibited the cytotoxic effects on gastric cancer cells in a dose-dependent manner. NTDMNQ significantly induced mitochondrial-related apoptosis in AGS cells and increased the accumulation of ROS. However, pre-treatment with N-acetyl-L-cysteine (NAC), an ROS scavenger, inhibited the NTDMNQ-induced apoptosis. In addition, NTDMNQ increased the phosphorylation of p38 kinase and c-Jun N-terminal kinase (JNK) and decreased the phosphorylation of extracellular signal-regulated kinase (ERK), protein kinase B (Akt), and Signal Transducer and Activator of Transcription 3 (STAT3); these effects were blocked by mitogen-activated protein kinase (MAPK) inhibitor and NAC. Taken together, the present findings indicate that NTDMNQ-induced gastric cancer cell apoptosis via ROS-mediated regulation of the MAPK, Akt, and STAT3 signaling pathways. Therefore, NTDMNQ may be a potential treatment for gastric cancer as well as other tumor types.

Evaluation of the Antimicrobial Activity and Cytotoxicity of Different Components of Natural Origin Present in Essential Oils

Even though essential oils (EOs) have been used for therapeutic purposes, there is now a renewed interest in the antimicrobial properties of phytochemicals and EOs in particular. Their demonstrated low levels of induction of antimicrobial resistance make them interesting for bactericidal applications, though their complex composition makes it necessary to focus on the study of their main components to identify the most effective ones. Herein, the evaluation of the antimicrobial action of different molecules present in EOs against planktonic and biofilm-forming Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria was assessed. The bactericidal mechanisms of the different molecules, as well as their cytocompatibility, were also studied. Carvacrol, cinnamaldehyde, and thymol exhibit the highest in vitro antimicrobial activities against E. coli and S. aureus, with membrane disruption the bactericidal mechanism identified. The addition of those compounds (≥0.5 mg/mL) hampers S. aureus biofilm formation and partially eliminates preformed biofilms. The subcytotoxic values of the tested EO molecules (0.015–0.090 mg/mL) are lower than the minimum inhibitory and bactericidal concentrations obtained for bacteria (0.2–0.5 mg/mL) but are higher than that obtained for chlorhexidine (0.004 mg/mL), indicating the reduced cytotoxicity of EOs. Therefore, carvacrol, cinnamaldehyde, and thymol are molecules contained in EOs that could be used against E. coli– and S. aureus–mediated infections without a potential induction of bactericidal resistance and with lower cell toxicity than the conventional widely used chlorhexidine.

In vitro effects of two major phenolic compounds from the family Lamiaceae plants on the human gastric carcinoma cells

Phenolic compounds of essential oils from the family Lamiaceae are commonly used substances in the food industry because of their flavouring, antimicrobial and antioxidant properties. In this context, it has become important to have healthy and safe products for consumers who are exposed to these phenolic compounds. The present study was aimed to investigate the toxic effects of carvacrol, thymol and their mixture on human gastric carcinoma (AGS) cells. Cells were analyzed after 24 h of exposure to different concentrations of carvacrol, thymol and their mixture by the ATP cell viability, 2',7' dichlorodihydrofluorescein diacetate (H2DCF-DA), reducte glutatione/oxide glutathione ((GSH)/GSSG-Glo) and comet assays. Apoptosis induction was studied by acridine orange/ethidium bromide staining and western blotting. Carvacrol, thymol and their mixture induced cytotoxicity, genotoxicity, apoptosis, increased reactive oxygen species (ROS) and decreased GSH levels after 24 h of their exposure in a dose-dependent manner. A close negative relationship was found between cell viability and ROS generation. We examined dose-dependent cytotoxic effects of carvacrol, thymol and their mixture in human AGS cells. Increased intracellular ROS causes oxidative stress in cells. The results indicated that these compounds should be used carefully in the food industry.

Characterization of phenolic extracts from Brava extra virgin olive oils and their cytotoxic effects on MCF-7 breast cancer cells

The aim of the present work was to evaluate the phenolic profile of the 'Brava' extra virgin olive oil and assess its potential as a "natural adjuvant" in combination with chemotherapy treatment. The total phenol content of the phenolic extracts was 764 mg gallic acid equivalents/kg and the total antioxidant capacity was 2309, 1881 and 2088 μM trolox equivalents/kg determined by Diphenyl-1-picrylhydrazyl free radical method, Ferric Reducing Antioxidant Power and Trolox Equivalent Antioxidant Capacity assay, respectively. Secoiridoids comprised 83% of the total phenolic compounds. The main secoiridoid from oleuropein was the main isomer of oleuropein aglycone (74 mg/kg). The main secoiridoid from ligstroside was the main isomer of ligstroside aglycone (214 mg/kg). These phenolic extracts showed a significant decrease in cell viability on MCF-7 breast cancer cells in a dose and time dependent manner. 48 h-treatments with different concentrations of the extracts induced intracellular ROS generation and cell death.

Carvacrol and human health: A comprehensive review

Carvacrol (CV) is a phenolic monoterpenoid found in essential oils of oregano (Origanum vulgare), thyme (Thymus vulgaris), pepperwort (Lepidium flavum), wild bergamot (Citrus aurantium bergamia), and other plants. Carvacrol possesses a wide range of bioactivities putatively useful for clinical applications such antimicrobial, antioxidant, and anticancer activities. Carvacrol antimicrobial activity is higher than that of other volatile compounds present in essential oils due to the presence of the free hydroxyl group, hydrophobicity, and the phenol moiety. The present review illustrates the state-of-the-art studies on the antimicrobial, antioxidant, and anticancer properties of CV. It is particularly effective against food-borne pathogens, including Escherichia coli, Salmonella, and Bacillus cereus. Carvacrol has high antioxidant activity and has been successfully used, mainly associated with thymol, as dietary phytoadditive to improve animal antioxidant status. The anticancer properties of CV have been reported in preclinical models of breast, liver, and lung carcinomas, acting on proapoptotic processes. Besides the interesting properties of CV and the toxicological profile becoming definite, to date, human trials on CV are still lacking, and this largely impedes any conclusions of clinical relevance.

Effects of carvacrol on human fibroblast (WS-1) and gastric adenocarcinoma (AGS) cells in vitro and on Wistar rats in vivo

Carvacrol is a natural phenolic compound found in essential oils of Lamiaceae species. In the present study, an attempt has been made to elucidate the mechanism behind the anti-cancer potential of carvacrol on human gastric adenocarcinomas (AGS) by comparing its effects on cancer cells AGS to those on normal human fibroblast (WS-1) cells, in vitro. Cytotoxicity, reactive oxygen species (ROS) generation, glutathione (GSH) levels, genotoxicity, and apoptotic effects of carvacrol (0-600 µM) were studied in both cell lines. Additionally, the effect of high dose carvacrol (100 mg/kg BW) on the oxidative status was investigated in vivo. For this purpose, carvacrol was administered orally to male Wistar rats over a period of 60 days. Rats were weighed regularly. At the end of the experiment, rats were euthanized. Blood and stomach tissues were collected for biochemical and pathological examinations. The in vitro results showed significant differences in cell viability of AGS compared to WS-1 cells exposed to carvacrol. Also the extent of ROS generation, GSH reduction and DNA damage differed significantly between the cell lines studied (P ≤ 0.001). The differences observed were statistically significant at all concentrations applied (P ≤ 0.001). The results found in AGS cells were mirrored in the pathohistological findings obtained from animals of the in vivo experimental group. Changes in body weight, and oxidative stress index for plasma and stomach tissues of animals in this group were found to differ statistically significant from those found in the control group of Wistar rats (P ≤ 0.001). The data obtained from our present study uncovered that carvacrol has the potential to cause toxic effects in both, AGS and WS-1 cells but more effectively in cancer cells than in normal cells. The carvacrol-mediated responses observed in the in vitro and in vivo experiments presented suggest a double-edged pro-oxidative effect. Via this mechanism carvacrol induced cytotoxicity, apoptosis, and DNA damage in a dose-dependent manner in both cancer and normal cells and these activities were higher in cancer cells than those of normal cells.